Read default.yml runtime configuration file after package install

[ptgrogan]

Resolve error in #92 by identifying root cause behind runtime configuration file not loading after package-based install (probably a file path issue).

[suvan-kumar]

@ptgrogan, Sphinx searches for a conf.py file, as opposed to config.py -- Sphinx Documentation. I believe this is the issue, but there could be more going on. If it is, there are a couple different options for getting it to work without renaming the file, but the easiest solution is renaming the file to conf.py. I can test this out later if there are any issues.

[ptgrogan]

@suvan-kumar I didn't provide much details in the issue; it is completely separate from anything related to Sphinx (at least I assume so). We added a new runtime configuration feature load/store defaults in TAT-C. The default runtime configurations are specified in src/tatc/resources/default.yml but it seems there are problems loading. I added a try/except to build defaults from a Pydantic object model until the load-from-file issue is resolved. The problem probably has to do with file path.

[ptgrogan]

(The src/tatc/config.py file contains the runtime configurations specification including the loader)